Tibial prosthesis for tibia with varus resection

ABSTRACT

Methods, systems and apparatuses are disclosed including apparatuses that can be used in a total knee replacement procedure. According to one example, a tibial implant is disclosed. The tibial implant can be configured for attachment to a tibia in a knee arthroplasty and can include a baseplate having a lateral portion and a medial portion oriented relative to an anteroposterior axis and a fixation member. Each of the lateral portion and the medial portion can have a distal surface configured to interface with a resected proximal surface of a tibia. The fixation member can be coupled to and extend both distally and medially from the baseplate such that the fixation member is oriented at an acute angle relative to the distal surface of the medial portion.

CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/267,826, filed on Sep. 16, 2016, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/234,141, filed on Sep. 29,2015, the benefit of priority of which is claimed hereby, and which isincorporated by reference herein in its entirety.

FIELD

The present subject matter relates to orthopedic procedures and, moreparticularly, to tibial implants used in some knee arthroplasties wherea varus resection of a tibia is utilized.

BACKGROUND

Orthopedic procedures and prostheses are commonly utilized to repairand/or replace damaged bone and tissue in the human body. For example, aknee arthroplasty can be used to restore natural knee function byrepairing damaged or diseased articular surfaces of the femur and/ortibia. An incision is made into the knee joint to expose the bonescomprising the joint. Cut guides are used to guide the removal of thearticular surfaces that are to be replaced. Prostheses are used toreplicate the articular surfaces. Knee prostheses can include a femoralcomponent implanted on the distal end of the femur, which articulateswith a tibial component implanted on the proximal end of a tibia toreplicate the function of a healthy natural knee. Various types ofarthroplasties are known including a total knee arthroplasty (TKA),where all of the articulating compartments of the joint are repairedwith prosthetic components.

Overview

The present inventor recognizes, among other things, an opportunity forreducing trauma to the lateral tibial metaphysis and/or lateral tibialdiaphysis during a TKA. More particularly, the present inventor hasrecognized that traditional fixation members for the tibial componentsuch as a stem, keel, and/or fins may not be appropriately referenced toa central axis of the intramedullary canal. A result of suchmisalignment is that the fixation member does not reference down thecenter of the intramedullary canal. This misalignment can result in thefixation member perforating the lateral metaphysis or lateral diaphysiswhen the tibial component is seated down into a position on top of theresected proximal end of the tibia. The present inventor proposes atibial implant, methods, and systems where the fixation member isappropriately referenced to substantially align with the central axis ofthe intramedullary canal. Achieving this orientation can include havingthe fixation member(s) extend both distally and medially from abaseplate of the tibial implant such that the fixation member isoriented at an acute angle (i.e. be oriented in valgus) relative to theresected proximal surface (corresponding to a distal surface of a medialportion of the baseplate).

To further illustrate the apparatuses, systems and methods disclosedherein, the following non-limiting examples are provided:

In Example 1, a tibial implant configured for attachment to a tibia in aknee arthroplasty is disclosed. The tibial implant can be configured forattachment to a tibia in a knee arthroplasty and can include a baseplatehaving a lateral portion and a medial portion oriented relative to ananteroposterior axis and a fixation member. Each of the lateral portionand the medial portion can have a distal surface configured to interfacewith a resected proximal surface of a tibia. The fixation member can becoupled to and extend both distally and medially from the baseplate suchthat the fixation member is oriented at an acute angle relative to thedistal surface of the medial portion.

In Example 2, the tibial implant of Example 1, wherein the fixationmember can comprise one or both of a keel and a stem that are configuredfor insertion into a metaphysis and/or diaphysis of the tibia.

In Example 3, the tibial implant of Example 2, wherein one or both ofthe keel and stem can be configured to be removably attached to thebaseplate.

In Example 4, the tibial implant of Example 3, wherein one or both ofthe keel and stem can be configured to be adjustable 180° relative tothe baseplate such that the tibial implant can be configured for usewith both a left tibia and a right tibia.

In Example 5, the tibial implant of Example 2, wherein the stem and keelcan be configured to couple together, and wherein the stem can beconfigured to couple to the baseplate at the acute angle and coupling ofthe keel with the stem orients the keel at substantially a same acuteangle relative to the distal surface of the medial portion as the acuteangle.

In Example 6, the tibial implant of Example 2, wherein the stem and keelcan be configured to couple together, and wherein the keel can beconfigured to couple to the baseplate at the acute angle and coupling ofthe stem with the keel orients the stem at substantially a same acuteangle relative to the distal surface of the medial portion as the acuteangle.

In Example 7, the tibial implant of any one or any combination ofExamples 1-6, wherein the fixation member can include a symmetricfeature having an axis of symmetry, and wherein the acute angle can bemeasured between the axis of symmetry and the distal surface of themedial portion.

In Example 8, the tibial implant of any one or any combination ofExamples 1-7, wherein the fixation member can include a lateral portionand a medial portion, and wherein the medial portion has a greatersurface area than the lateral portion.

In Example 9, the tibial implant of any one or any combination ofExamples 1-8, wherein the baseplate and fixation member can beconfigured such that the fixation member is adjustable 180° relative tothe baseplate such that the tibial implant is configured for use withboth a left tibia and a right tibia.

In Example 10, a system for forming a tibial implant configured forattachment to a tibia in a knee arthroplasty is disclosed. The systemcan include one or more baseplates and a plurality of fixation members.The one or more baseplates can have a lateral portion and a medialportion oriented relative to an anteroposterior axis. Each of thelateral portion and the medial portion can have a distal surfaceconfigured to interface with a resected proximal surface of a tibia.Each of the plurality of fixation members can be configured to couple tothe baseplate and can extend both distally and medially from thebaseplate such that each fixation member of the plurality of fixationmembers is oriented at an acute angle relative to the distal surface ofthe medial portion. Each of the plurality of fixation members can beconfigured to differ from others of the plurality of fixation memberssuch that the acute angle formed by each of the plurality of fixationmembers, when mounted to the baseplate, differs in degree.

In Example 11, the system of Example 10, wherein the plurality offixation members can comprise a plurality of keels each having adifferent configuration and a single stem having a single configuration,wherein the single stem is configured to universally couple with any ofthe plurality of keels.

In Example 12, the system of Example 10, wherein the plurality offixation members can comprise a plurality of stems each having adifferent configuration and a single keel having a single shape, whereinthe single keel can be configured to universally couple with any of theplurality of stems.

In Example 13, the system of any one or any combination of Examples10-12, wherein the baseplate and fixation member can be configured suchthat the fixation member can be coupled to the baseplate in at least twoorientations including to create a first configuration for a right kneeand a second configuration for a left knee.

In Example 14, a method of performing a knee arthroplasty is disclosed.The method can include resecting a proximal surface of a tibia to exposea tibial metaphysis, and attaching a tibial implant to the resectedsurface at a distal surface of a baseplate of the tibial implant, thetibial implant having a fixation member that is configured to generallyalign with a central axis of the tibial diaphysis when coupled to thedistal surface of the baseplate.

Example 15, the method of Example 14, can further comprise determining adesired angle based on degree of varus between the distal surface of thebaseplate and the central axis of the tibial diaphysis, selecting from aplurality of fixation members that are configured to achieve the desiredangle when coupled to the baseplate, and coupling the selected fixationmember to the tibial baseplate.

In Example 16, the method of any one or any combination of Examples 14and 15, wherein the plurality of fixation members can comprise aplurality of keels and a single stem configured to universally couplewith all of the plurality of keels.

Example 17, the method of any one or any combination of Examples 14 and15, wherein the plurality of fixation members can comprise a pluralityof stems and a single keel configured to universally couple with all ofthe plurality of stems.

In Example 18, a tibial implant configured for attachment to a tibia ina knee arthroplasty is disclosed. The tibial implant can include abaseplate, a keel, and a stem. The baseplate can have a lateral portionand a medial portion oriented relative to an anteroposterior axis, eachof the lateral portion and the medial portion having a distal surfaceconfigured to interface with a resected proximal surface of a tibia. Thekeel can be coupled to and extending both distally and medially from thebaseplate such that the keel creates an acute angle between the keel andthe distal surface of the medial portion. The stem can be configured tocouple with one or both of the keel and the baseplate and configured toremovably insert within a receptacle of the keel to be oriented at theacute angle relative to the distal surface of the medial portion.

In Example 19, the tibial implant of Example 18, wherein the keel cancomprise one of a plurality of keels each keel configured to form adifferent degree of acute angle when coupled to the baseplate.

Example 20, the tibial implant of Example 18, wherein the stem cancomprise one of a plurality of stems each stem configured to form adifferent degree of acute angle when coupled to the baseplate.

In Example 21, the tibial implant of any one or any combination ofExamples 18-20, wherein the baseplate, keel, and stem are eachconfigured such that at least one of the keel and stem is adjustable180° relative to the baseplate such that the tibial implant isconfigured for use with both a left tibia and a right tibia.

In Example 22, the apparatuses or method of any one or any combinationof Examples 1-21 can optionally be configured such that all elements oroptions recited are available to use or select from.

These and other examples and features of the present apparatuses,systems and methods will be set forth in part in the following DetailedDescription. This Overview is intended to provide non-limiting examplesof the present subject matter—it is not intended to provide an exclusiveor exhaustive explanation. The Detailed Description below is included toprovide further information about the present apparatuses and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralscan describe similar components in different views. Like numerals havingdifferent letter suffixes can represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various examples discussed in the presentdocument.

FIG. 1A is a frontal or coronal plane view of a knee joint with animplanted knee prosthesis according to an example of the presentapplication.

FIG. 1B is a coronal view of the knee joint and knee prosthesis of FIG.1A in 90 degrees flexion according to an example of the presentapplication.

FIG. 1C is a side or sagittal plane view of the knee joint and kneeprosthesis of FIGS. 1A and 1B in full extension according to an exampleof the present application.

FIG. 2 is a coronal plane view of a tibia and a femur for a right kneehaving implants thereon and showing orientations of the implantsrelative to axes of the knee according to an example of the presentapplication.

FIG. 3A is a plan view of a proximal side of a tibial implant for a leftknee according to an example of the present application.

FIG. 3B is a perspective view of a distal portion of the tibial implantof FIG. 3A illustrating a fixation member canted relative to a distalsurface of a baseplate according to an example of the presentapplication.

FIG. 4 is a view of an assembly in a coronal plane including the tibialimplant of FIGS. 3A and 3B and a stem according to an example of thepresent application.

FIG. 5 is a view of two assemblies including tibial implants and othercomponents according to an example of the present application.

FIG. 6 is a view of two assemblies including tibial implants and othercomponents according to another example of the present application.

FIG. 7A is a plan view of a distal side of a tibial implant according toyet another example of the present application.

FIG. 7B is a plan view of a fixation member in two orientationsaccording to example of the present application.

FIG. 7C is a coronal plan view of the tibial implant of FIG. 7A coupledto the fixation member of FIG. 7B with the fixation member in a firstorientation such as is shown in FIG. 7B and with the fixation member ina second orientation such as is shown in FIG. 7B according to an exampleof the present application.

DETAILED DESCRIPTION

It has been established that a kinematically aligned TKA can improve theresults of the TKA, including overall patient satisfaction and mobility.Primary goals of kinematically aligned TKA are (1) positioning thefemoral and tibial components of a knee prosthesis such that the anglesand levels of the distal and posterior femoral and tibial joint linesare restored to the patient's natural joint line, (2) restoration of thepatient's natural or constitutional alignment prior to the patienthaving developed osteoarthritis, and (3) restoration of the patient'snatural soft tissue laxity and envelope. The kinematically aligned TKAcan include a determination of three kinematic axes.

FIGS. 1A-1C show various views of a knee prosthesis 10 implanted on aknee joint and illustrate the three kinematic axes of the knee joint ina kinematically, aligned TKA. In particular, FIG. 1A provides a view ofthe knee prosthesis 10 in a coronal plane as viewed from the anteriorwith a femoral component 12 in extension. FIG. 1B is a view of the kneeprosthesis 10 in the coronal plane with the femoral component 12 inflexion. FIG. 1C is a view of the 10 in the sagittal plane with thefemoral component in extension. The femoral component 12 is implanted ona femur 14 while a tibial component 16 implanted on a tibia 18. Apolyethylene surface is inserted between the femur and tibia. A firstkinematic axis 20 can be a transverse axis in the femur 14 about whichthe tibia 18 flexes and extends. The first kinematic axis 20 can bedetermined by projecting the lateral and medial femoral condyles of thefemur 14 onto one another and fitting circles of equal radii over eachother. The first kinematic axis 20 passes through a center of thecircles. A second kinematic axis 22 can be a second transverse axis,parallel to the first kinematic axis 20, about which a patella of theknee joint flexes and extends. The second kinematic axis 22 can belocated anterior and proximal to the first kinematic axis 20. A thirdkinematic axis 24 is an axis perpendicular to the first 20 and second 22axes about which the tibia 18 internally and externally rotates on thefemur 14.

The present application does not include a description of the surgicalprocedure for performing a kinematically aligned TKA. Such proceduresare discussed, for example, in relation to application Ser. No.14/809,810, entitled “INSTRUMENTS AND METHODS IN PERFORMINGKINEMATICALLY-ALIGNED TOTAL KNEE ARTHROPLASTY” filed Jul. 27, 2015, andSer. No. 13/819,528, entitled “FEMORAL PROTHESIS WITH MEDIALIZEDPATELLAR GROOVE”, filed Sep. 9, 2011, the entire disclosures of whichare incorporated herein by reference and are co-owned by the Applicant.Rather, FIGS. 2-7C provide examples of surgical instruments, systems,methods and techniques that can be used to aid and improve on thekinematically aligned TKA.

FIG. 2 shows an example of a TKA knee prosthesis 110 in a right knee ofa patient as viewed in the coronal plane. As was generally discussedwith respect to FIGS. 1A-1C, the knee prosthesis 110 can include afemoral component 112 mounted to the femur 14 and a tibial component 116mounted to the tibia 18. FIG. 2 shows the knee prosthesis 110 alignmentrelative to the anatomical axes of the femur 14 and the tibia 18. Inparticular, FIG. 2 shows a femoral anatomical axis 120 and a tibialanatomical axis 122.

Disposition of the femoral component 112 relative to the femoralanatomical axis 120 is indicated by a as measured between a line 124across the bottom of the femoral condyles 113A and 113B the femoralshaft axis (superimposed with the femoral anatomical axis 120).Disposition of the tibial component 116 relative to the tibialanatomical axis 122 is indicated by β as measured between a line 126across a base of a tibial plate 128 of the tibial component 116 and atibial shaft axis (superimposed with the tibial anatomical axis 122). Anangle Δ (a tibiofemoral axis) is also indicated and comprises a measurebetween the femoral shaft axis and the tibial shaft axis.

An α of 90° comprises a neutral placement of the femoral component 112,α<90° corresponds to varus placement of the femoral component 112, andα>90° corresponds to valgus placement of the femoral component 112.Similarly, if β=90° corresponds to a neutral placement of the tibialcomponent 116, β<90° corresponds to varus placement of placement of thetibial component 116, and β>90° corresponds to valgus placement of thetibial component 116. If Δ=180° this corresponds to a neutral alignment,Δ<180° corresponds to varus alignment, and Δ>180° corresponds to valgusalignment.

With regard to coronal alignment of the femoral component 112, it hasgenerally been shown that an optimal distal femoral cut is typically2-7° of valgus. With regard to coronal alignment of the tibial component116, a certain degree of varus tibial alignment with a varus cut isgenerally desirable. With the kinematically aligned TKA it has generallybeen found that tibial component 116 placement of a few more degreesvarus (e.g., about 0.1 degrees to about 5 degrees) and the femoralcomponent 112 placed in a few more degrees valgus (e.g., about 0.1degrees to about 5 degrees) than traditional mechanically aligned TKAresults in improved patient outcomes.

The present inventor has recognized that especially with the additionalvarus disposition of the tibial component 116 in the kinematicallyaligned TKA, traditional fixation members for the tibial component 116such as a stem, keel, or fins (e.g., a keel and stem 130 as shown inFIG. 2) may not be appropriately referenced to the intramedullary canalwhich generally aligns with the tibial anatomical axis 122. Indeed, anexample of such misalignment is shown in FIG. 2 where the keel 130 isnot substantially aligned with the tibial anatomical axis 122. A resultof such misalignment is that the keel 130 does not reference down thecenter of the tibial diaphysis/intramedullary canal. This misalignmentcan result in the keel 130 perforating the lateral metaphysis or lateraldiaphysis when the tibial component 116 is seated down into a positionon top of the resected proximal end surface 132 of the tibia 18.

FIGS. 3A and 3B show an example tibial implant 210 configured for a leftknee (note difference from the configuration of FIG. 2 which isconfigured for the right knee). According to further examples theexample of FIGS. 3A and 3B can be mirrored for use with the right knee.The tibial implant 210 includes a baseplate 212 and a fixation member214 (FIG. 3B). The baseplate 212 includes a proximal surface 216 (FIG.3A), a distal surface 218 (FIG. 3B), an anterior edge 220, a posterioredge 222, an anteroposterior axis 224, a lateral portion 226, and amedial portion 228. The fixation member 214 shown in FIG. 3B comprises akeel 230 and fins 232A and 232B. The keel 230 includes a medial portion234, a lateral portion 236, and a receptacle 238.

In the example provided, the baseplate 212 and fixation member 214 arecoupled together. As shown in FIG. 3A, the baseplate 212 can beconfigured at the proximal surface 216 to receive a tibial bearingcomponent, for example. The distal surface 218 is disposed on anopposing side of the baseplate 212 from the proximal surface 216 and canbe configured to interface with a resected proximal surface of a tibia.The distal surface 218 can include a medial portion 218A (correspondingto that of the medial portion 226) and a lateral portion 218B(corresponding to that of the lateral portion 228). Both the proximalsurface 216 and the distal surface 218 extend from the anterior edge 220to the posterior edge 222 of the baseplate 212.

As shown in FIG. 3A the anteroposterior axis 224 can divide thebaseplate 212 into the medial portion 226 and the lateral portion 228.Thus, the medial portion 226 and the lateral portion 228 can be orientedrelative to the anteroposterior axis 218. Although shown with anasymmetrically shaped medial portion 226 relative to the lateral portion228, in some examples the medial portion 226 and the lateral portion 228can be substantially symmetric relative to one another.

As shown in the example of FIG. 3B, the fixation member 214 can becoupled to and can extend both distally and medially from the distalsurface 218 such that the fixation member 214 is oriented at an acuteangle θ (FIG. 4) relative to the distal surface 218A of the medialportion 226 when viewed in the frontal or coronal plane. Put another waywith reference to FIG. 2 for terminology and points of reference, thefixation member 214 can be provided with an angle (β>90° in reference tothe tibial anatomical axis 122) to compensate for the varus orientationof the baseplate 212 on the resected proximal end surface 132 of thetibia 18. Thus, the fixation member 214 can configured to substantiallyalign with a central axis (indicated by tibial anatomical axis 122 ofFIG. 2) of the tibial diaphysis when the fixation member 214 is coupledto the distal surface 218 of the baseplate 212. This orientation of thefixation member reduces the risk that the fixation member 214 willperforate the lateral metaphysis or lateral diaphysis when the tibialcomponent 210 is seated down into a position on top of the resectedproximal end surface 132 of the tibia 18.

As shown in the example of FIG. 3B, the fixation member 214 isconfigured as a keel 230, however in other examples the fixation member214 can comprise some other type of projection (e.g., a stem, a peg, orthe like) that is configured for insertion into the metaphysis ordiaphysis of the tibia. According to the example of FIG. 3B, the keel230 can have fins 232A and 232B extending to the medial portion 226 andlateral portion 228, respectively. Additionally, the keel 230 can havethe medial portion 234 be differently configured than the lateralportion 236. For example, the lateral portion 236 can have a greatersurface area than the medial portion 234 as shown in the illustratedexample of FIG. 3B due to the angling of the fixation member 214relative to the distal surface 318 of the baseplate 212. Such anglingcan provide the lateral portion 236 with a greater distal extent than adistal extent of the medial portion 234.

As shown in FIG. 3B, the keel 230 can form the receptacle 238 whichextends through a substantial portion of the keel 230. The receptacle238 can receive a stem such as a stem 240 of FIGS. 4 and 5, for example.Further disclosure of various examples of keels with stems includingcoupling mechanisms between these two components and/or the baseplateare provided in United States Patent Application Publication2013/0024001, entitled “ASYMMETRIC TIBIAL COMPONENTS FOR A KNEEPROSTHESIS”, filed Jan. 23, 2013 and by U.S. Pat. No. 7,691,150,entitled “MODULAR PLATE AND KEEL PROVISONALS”, filed Dec. 14, 2006, theentire disclosures of both of which are incorporated herein byreference.

FIG. 4 shows an assembly 208 of the tibial implant 210 from FIGS. 2A and2B with the stem 240 that can be configured to be received in thereceptacle 238. Thus, the stem 240 is configured to be insertable intothe keel 230 to couple together the stem 240 and the keel 230. One orboth of the keel 230 and the stem 240 are configured to be removablyattached to the baseplate 212. In the example of FIG. 4, the keel 230has a female mating option (receptacle 238) where the stem 240 can beselected as a male counterpart. However, other configurations will bediscussed subsequently. Thus, the keel 230 can be configured to coupleto the baseplate 212 at the acute angle θ and coupling of the stem 240with the keel 230 orients the stem 240 at substantially a same acuteangle relative to the distal surface 218A of the medial portion 226 asthe acute angle θ of the keel 230. In FIG. 4, the fixation member 214includes a symmetric feature (e.g. the receptacle 238 and the stem 240)each having an axis of symmetry A. The acute angle θ can extend betweenthe axis of symmetry A and the distal surface 218A of the medial portion226.

Furthermore, FIGS. 3A to 4 illustrate an example where the keel 230 canbe integrally formed with the baseplate 212 such that the two componentscomprise a single component. However, in other examples the keel 230 canbe affixed by other mechanisms (weld, thread, interference fit, or thelike) some of which allow the keel to be removable from the baseplate.

FIG. 5 shows components that can comprise assemblies 308 and 408. Inparticular, when assembled together the components can comprise a tibialimplant similar to those previously shown and discussed herein. As shownin the example of FIG. 5, the assemblies 308, 408 can include at leastone baseplate (e.g., baseplate 312 and baseplate 412). As with priordiscussed embodiments, each baseplate 312, 412 can have a medial portion326, 426 and a lateral portion 328, 428. Furthermore, each of the medialportion 326, 426 and the lateral portion 328, 428 can have a distalsurface 318, 418 configured to interface with a resected proximalsurface of a tibia.

The assemblies 308, 408 also can include at least one of a plurality offixation members 314, 414. Each of the plurality of fixation members314, 414 can be configured to attach to and extend both distally andmedially from the distal surface 318, 418 such that each fixation member314, 414 of the plurality of fixation members 314, 414 is oriented at anacute angle θ₁, θ₂ relative to the distal surface 318A, 418A of themedial portion 326, 426 when viewed in the frontal or coronal plane.Each of the plurality of fixation members 314, 414 can be configured todiffer from others of the plurality of fixation members 314, 414 suchthat the acute angle θ₂, θ₁ formed by each of the plurality of fixationmembers 314, 414 when coupled to the baseplate 312, 412 would differ indegree.

More particular, a keel 330, 430 can be coupled to and extend bothdistally and medially relative to the distal surface 318, 412 such thatthe keel 330, 430 creates the acute angle θ₁, θ₂ between the keel 330,430 and the distal surface 318A, 418A of the medial portion 326, 426when viewed in the frontal or coronal plane. A stem 340 can beconfigured to couple with one or both of the keel 330, 430 and thebaseplate 312, 412 and can be configured to removably insert within areceptacle 338, 438 of the keel 330, 430.

It should be noted that although illustrated as assemblies 308, 408 thatinclude almost entirely separate components, in some examples acomponent such as one or more of the baseplates 312, 412, keels 330,430, and/or stem 340 can be configured to universally couple with othersof the components. For example, in FIG. 5 the plurality of fixationmembers 314, 414 can comprise a plurality of keels 330, 430 (each keel330, 430 can have a different configuration) and a single stem 340. Thesingle stem 340 can have only a single configuration and can beconfigured to universally couple with any of the plurality of keels 330,430. As shown in FIG. 5, the keels 330, 430 can comprise one of aplurality of keels (e.g., 330, 430, and so on) each keel 330, 430 can beconfigured to form a different acute angle (e.g., θ₁, θ₂, and so on)when coupled to the baseplate 312, 412. Although a plurality ofbaseplates 312, 412 are shown in FIG. 5, in some examples a singlebaseplate can be utilized with the assemblies and can be configured tocouple to any of the plurality of keels (e.g., 330, 430).

FIG. 6 shows assemblies 508, 608 according to further examples.According to the examples of FIG. 6, the assemblies 508, 608 can includeat least one baseplate (e.g., baseplate 512 and baseplate 612). As withprior discussed embodiments, each baseplate 512, 612 can have a medialportion 526, 626 and a lateral portion 528, 628 oriented relative to ananteroposterior axis (not shown). Furthermore, each baseplate 512, 612can have a distal surface 518, 618 configured to interface with aresected proximal end surface 132 (FIG. 2) of a tibia.

The assemblies 508, 608 also can include at least one of a plurality offixation members 514, 614. Each of the plurality of fixation members514, 614 can be configured to attach to and extend both distally andmedially from the distal surface 518, 618 such that each fixation member514, 614 of the plurality of fixation members 514, 614 is oriented at anacute angle δ₁, δ₂ relative to the distal surface 518A, 618A of themedial portion 526, 626 when viewed in the frontal or coronal plane.Each of the plurality of fixation members 514, 614 can be configured todiffer from others of the plurality of fixation members 514, 614 suchthat the acute angle δ₁, δ₂ formed by each of the plurality of fixationmembers 514, 614 when mounted to the baseplate 512, 612 would differ indegree. The examples of FIG. 6 utilize a plurality of stems 540, 640 anda single keel 530. Each stem 540, 640 can be configured to couple to thebaseplate 512 and/or 612 at the acute angle δ₁, δ₂. Coupling of the keel530 with the stem 540 can orient the keel 530 at substantially a sameacute angle relative to the distal surface 518A, 618A of the medialportion 526, 626 as the acute angle δ₁, δ₂.

It should be noted similar to assemblies 308, 408 the assemblies 508,608 can be have one or more components configured to universally couplewith others of the components of the assemblies 508, 608. For example,in FIG. 6 the plurality of fixation members 514, 614 can comprise theplurality of stems 540, 640 (each keel 330, 430 can have a differentconfiguration) and a single keel 530. Thus, according to some examplesthe keel 530 can have only a single configuration and can be configuredto universally couple with any of the plurality of stems 540, 640. Asshown in FIG. 6, the stems 540, 640 can comprise one of a plurality ofstems (e.g., 540, 640, and so on) each keel 540, 640 can be configuredto form a different acute angle (e.g., δ₁, δ₂, and so on) when coupledto the baseplate 512, 612.

An example method of performing a knee arthroplasty using a tibialimplant such as those discussed herein can include resecting a proximalsurface of a tibia to expose a tibial metaphysis, and attaching a tibialimplant to the resected surface at a distal surface of a baseplate ofthe tibial implant. The tibial implant can have a fixation member whichis configured to generally align with a central axis of the tibialdiaphysis (e.g., indicated by tibial anatomical axis 122 of FIG. 2) whencoupled to the distal surface of the baseplate. According to furtherexamples the method can include determining a desired angle based ondegree of varus between the distal surface of the baseplate and thecentral axis of the tibial diaphysis, selecting from a plurality offixation members that are configured to achieve the desired angle whencoupled to the baseplate, and coupling the selected fixation member tothe tibial baseplate.

FIGS. 7A to 7C show another example of a tibial implant 710 where abaseplate 712 and fixation member 714 are configured such that thefixation member 714 is adjustable relative to the baseplate 712. Thetibial implant 710 can include the baseplate 712 and the fixation member714 similar to those previously described. Thus, the baseplate 712 caninclude a distal surface 718 and the fixation member 714 can comprise astem 740 (FIGS. 7B and 7C) configured to mate with one or more keels(not shown). However, the baseplate 712 can also include a couplingfeature 720 (FIG. 7A) disposed at the distal surface 718.

The coupling feature 720 can be configured to couple with a base 722(FIG. 7B) of the stem 740 with the base 722 and the stem 740 assembly inmultiple orientations. As illustrated and described according to theexample of FIGS. 7A to 7C, the stem 740 can be configured to beadjustable 180° relative to the baseplate 712 by simply reversing theorientation of the base 722 (shown in FIG. 7B) and then recoupling thebase 722 and the stem 740 to the baseplate 712. Therefore, FIGS. 7A to7C show an example where the baseplate 712 and fixation member 714 thatare configured such that the fixation member 714 can be coupled to thebaseplate 712 in at least two orientations including to create a firstconfiguration for a right knee and a second configuration for a leftknee. According to other examples, rather than being configured to beadjustable 180° relative to the baseplate, the fixation member can beclocked to be incrementally adjustable both in the medial-lateraldirection but also in the anterior-posterior direction. Thus, in someexamples the fixation member can be re-orientable relative to thebaseplate to form a plurality of different configurations.

More particularly, the coupling feature 720 can comprise fixationmechanisms known in the art such as those that use a slot, groove,flange, male/female connection, interference, tab, fastener, pin, orother mechanisms to couple the base 722 to the baseplate 712. Accordingto the example of FIG. 7A, the coupling feature 720 comprises grooves724 adapted to receive corresponding features of the base 722 which isinserted from a posterior toward an anterior of the baseplate 712. Afastener (not shown) can be received in hole 726 in the baseplate 712and can insert into or abut the base 722 once the base 722 is moved intothe desired position. This can further lock the base 722 relative to thebaseplate 712. FIG. 7A provides only one example of a coupling featureothers including those that utilize a different insertion directionand/or coupling mechanism(s) are contemplated.

Additional Notes

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) can be used in combination with each other. Otherexamples can be used, such as by one of ordinary skill in the art uponreviewing the above description. The Abstract is provided to comply with37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the natureof the technical disclosure. It is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. Also, in the above detailed description, various features can begrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter can lie in lessthan all features of a particular disclosed example. Thus, the followingclaims are hereby incorporated into the detailed description as examplesor embodiments, with each claim standing on its own as a separateexample, and it is contemplated that such examples can be combined witheach other in various combinations or permutations. The scope of theinvention should be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled.

The invention claimed is:
 1. A tibial implant configured for attachmentto a tibia in a knee arthroplasty, the tibial implant comprising: abaseplate having a lateral portion and a medial portion orientedrelative to an anteroposterior axis, each of the lateral portion and themedial portion having a distal surface configured to interface with aresected proximal surface of a tibia; and a fixation member configuredto couple with and extending both distally and medially from thebaseplate such that the fixation member is oriented at an acute anglerelative to the distal surface of the medial portion, wherein thefixation member comprises a keel and a stem configured for insertioninto a metaphysis and/or diaphysis of the tibia, and wherein at leastone of the keel and stem are removably attachable to the baseplate andconfigured to be 180° reversible relative to the baseplate so as to haveonly two possible orientations when attached to the baseplate, whereby,the tibial implant is configured for use with both a left tibia and aright tibia.
 2. The tibial implant of claim 1, wherein the stem and keelare configured to couple together, and wherein the stem is configured tocouple to the baseplate at the acute angle and coupling of the keel withthe stem orients the keel at substantially a same acute angle relativeto the distal surface of the medial portion as the acute angle.
 3. Thetibial implant of claim 1, wherein the stem and keel are configured tocouple together, and wherein the keel is configured to couple to thebaseplate at the acute angle and coupling of the stem with the keelorients the stem at substantially a same acute angle relative to thedistal surface of the medial portion as the acute angle.
 4. The tibialimplant of claim 1, wherein the fixation member includes a symmetricfeature having an axis of symmetry, and wherein the acute angle ismeasured between the axis of symmetry and the distal surface of themedial portion.
 5. The tibial implant of claim 1, wherein the fixationmember includes a lateral portion and a medial portion, and wherein themedial portion has a greater surface area than the lateral portion. 6.The tibial implant of claim 1, wherein the baseplate and fixation memberare configured such that the fixation member is adjustable 180° relativeto the baseplate such that the tibial implant is configured for use withboth a left tibia and a right tibia.
 7. A tibial implant configured forattachment to a tibia in a knee arthroplasty, the tibial implantcomprising: a baseplate having a lateral portion and a medial portionoriented relative to an anteroposterior axis, each of the lateralportion and the medial portion having a distal surface configured tointerface with a resected proximal surface of a tibia; a stem configuredto couple with the baseplate and extending both distally and mediallyfrom the baseplate such that the stem is oriented at an acute anglerelative to the distal surface of the medial portion; and a keelconfigured to couple with the stem, wherein coupling of the keel withthe stem orients the keel at substantially a same acute angle relativeto the distal surface of the medial portion as the acute angle of thestem, wherein at least one of the keel and stem are removably attachableto the baseplate and configured to be 180° reversible relative to thebaseplate so as to have only two possible orientations when attached tothe baseplate, whereby, the tibial implant is configured for use withboth a left tibia and a right tibia.